990
FXUS65 KPSR 062320
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Sat Sep 6 2025

.UPDATE...00Z Aviation Discussion.

&&

.KEY MESSAGES...

- Isolated chances for showers and thunderstorms continue into
  this evening with even lesser chances on Sunday.

- Slightly below normal temperatures this weekend will briefly
  warm back into the normal range early next week before dropping
  off again later next week.

- Localized Moderate Heat Risk is expected mainly across the
  south-central Arizona lower deserts during the first half of
  next week with highs as warm as 105 degrees.

&&

.SHORT TERM /Today through Sunday/...
Early afternoon satellite WV imagery showed a Pacific low well off
the coast of the Pacific Northwest continuing to pull drier air into
the region from the west while also promoting downstream
amplification of upper level ridging over the Desert Southwest.
Looking at this morning`s 12Z PHX sounding, this drying trend can be
seen aloft while moist conditions continue to linger in the boundary
layer. Despite the drier air and increasing subsidence over the
region, moisture and instability values remain favorable for
isolated convection this afternoon and evening, primarily over
terrain/orographic features such as the Kofas, Table Top, and areas
north and east of Phoenix. Primary concerns with any thunderstorms
that pop up today will be locally heavy rainfall and gusty winds.

The drying trend continues tomorrow and will essentially eliminate
rain chances from the forecast for most of our area with an isolated
chance for a shower/thunderstorm over the aforementioned
terrain/orographic features. Upper level ridging will continue to
build over the Southwest, leading to continued height rises
across the region and a gradual warming trend. Forecast highs
Sunday climb into the upper 90s to low 100s across the lower
deserts and low to mid 90s across higher elevation areas such as
Globe and San Carlos.

&&

.LONG TERM /Monday through Friday/...
The main driver of our weather early next week will be the
subtropical high centered just to our south, but the Pacific
trough off the West Coast will continue to bring westerly dry
flow into our region. H5 heights are forecast to peak early on
Monday at 592-594dm before gradually lowering through the middle
part of the week as the Pacific trough shifts closer to our
region. The higher heights and thicknesses should boost daytime
highs on Monday and Tuesday with highs anywhere from 100-105
degrees across the lower deserts. Overnight lows will also stay
quite elevated, contributing to localized Moderate HeatRisk
focused across the south-central Arizona lower deserts.

Ensemble guidance is in very good agreement bringing the Pacific
low center into northern California next Tuesday, displacing the
ridge that was over our region well to our southeast. H5 heights
are likely to fall to between 584-588dm by Wednesday potentially
staying in that range for a couple days late next week as the
trough likely stalls out over Nevada before lifting to the
northeast. This most likely scenario would continue to dry out the
boundary layer with surface dew points dropping into the 30s in
southeast California to the 40s in Arizona. Rain chances will stay
near zero through at least the first half of next week with only
a few members showing any slight rain chances at some point later
next week. Temperatures will also react to the incoming trough
with highs falling back into mid to upper 90s by around Wednesday
or Thursday and overnight lows falling below 80 degrees areawide.
It would not be surprising to see some low temperatures in the 60s
across rural lower deserts and into the 50s over higher terrain
areas. Lows within the Phoenix metro may eventually drop into the
low to mid 70s at some point later next week.

&&

.AVIATION...Updated at 2320Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are anticipated through the forecast period
with shower and thunderstorm activity remaining anchored to the
higher terrain N-NW of the Phoenix Metro. There is still a moderate
chance (30-50%) for a northerly outflow to arrive at KDVT and
KSDL around 03Z which will cause a brief N wind shift. Elsewhere,
westerly flow will prevail through this evening. Winds will shift
back out of the ESE at KPHX and KIWA late tonight before returning
out of the west by midday Sunday. FEW-SCT cloud decks between 6-8
kft AGL will be common during the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns will exist over the next 24
hrs. Winds will generally favor SE at KIPL and S at KBLH, with
sustained speeds to 8-15 kts through early this evening and
occasional gusts into the teens, particularly at KBLH. Winds will
relax overnight and may exhibit periods of variability Sunday
morning. FEW-SCT cloud decks around 6 kft AGL will be common
during the TAF period.

&&

.FIRE WEATHER...
High pressure will gradually take hold across the region through
the rest of this weekend into early next week leading to drying
conditions and diminishing rain chances. Isolated showers and
thunderstorms will remain primarily confined to terrain features
through this afternoon and evening with even lesser coverage
expected tomorrow. Humidities will remain elevated this weekend
before lowering early next week as MinRHs drop to below 30% by
Monday and 15-25% on Tuesday. Outside of any thunderstorm impacts,
winds will continue to be light and favor diurnal patterns
through early next week. Dry conditions with near zero rain
chances and MinRHs back into the teens are then likely for the
latter half of next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

SHORT TERM...Smith
LONG TERM...Kuhlman
AVIATION...Salerno
FIRE WEATHER...Smith/Kuhlman